The present invention relates to an apparatus and method for detecting the edge of a tool undergoing rapid periodic movement, and more particularly, to detecting the outermost cutting edge of a rotating grinding wheel.
Conventional grinding of surfaces in a workpiece can be accomplished by use of a grinding tool mounted on a jig grinder. The tool, of cylindrical configuration, is mounted on a rotatable spindle. The machine also has a spindle which moves relative to an X and Y-axis as well as vertically along a Z-axis, and can rotate about its own centerline which is known as the C-axis. The tool is independently movable relative to the C-axis along what is commonly termed the U-axis. The tool can also rotate about its own centerline. The movement of the tool along any combination of these axes (or other axes, as will be apparent to those skilled in the art) can be automatically controlled by a computerized program to grind the workpiece in a contoured predetermined pattern which will result in a contoured shape. Alternately, the grinding process can be performed manually. This invention relates to an apparatus and method for detecting the outermost cutting edge of a grinding tool or the like, so that proper dimensioning or sizing of a workpiece can be achieved.
In the past, contact of a tool edge with a workpiece or a fixed reference point was accomplished using visual, optical (e.g., laser), sound detection, or other mechanical or electromechanical detection techniques. In precision grinding or other precision machine tool applications, a tool edge may be moved in increments of several millionths of an inch. It is sometimes difficult to accurately detect the contact of a tool with a workpiece when working to such tolerances. Accordingly, it would be advantageous to provide an accurate method for detecting the edge of a tool undergoing rapid periodic movement (such as a rotating, and vertically reciprocating grinding wheel). It would be further advantageous to provide such an apparatus and method wherein an electrical control signal is produced in response to such tool edge detection.
The present invention relates to such an apparatus and method.